A known type of cable routing clip, which may be used in aircraft, is a so-called “P-Clip”. A P-Clip consists of a ring-shaped cable clamp, arranged to substantially surround a cable, and a tab, for receiving a fastener to attach the clip to a structure. The tab generally extends in a tangential direction relative to the ring-shaped clamp and, therefore, the clip has a cross-sectional shape that resembles the letter P. Two common forms of P-Clip are shown in FIGS. 1 and 2.
In the P-Clip of FIG. 1, the ring-shaped clamp 1 has a split 2 adjacent to the tab 4. The clamp 1 is attached to the tab 4 at one end and is provided with a closure tab 3 at its free end. A cable may be inserted into the clamp 1 through the split 2. A fastener 5 is then provided extending through aligned holes in the tabs 3, 4 to secure the clip to a structure and retain a cable therein.
In the alternate P-Clip of FIG. 2, the ring shaped clamp 1′ has a split 2′ which is positioned away from the tab 4′. In this arrangement, the clamp 1′ is formed of two arcuate members, each provided with a fastening tab 3′ at their free ends. The P-Clip of FIG. 2 may be secured to a structure using a fastener 5′ passing through the tab 4′. A cable may be inserted into the clamp 1′ via the split 2′ and the fastening tabs 3′ at free ends of the clamp are then connected to secure the cable.
When securing cabling within an aircraft structure it may be necessary to comply with certain safety requirements. For example, in certain regions of an airframe it may be a requirement that the failure of a cable routing clip does not result in the cable falling into a particular region of the structure. One such requirement is that a single failure does not allow the cable to touch the structure in a fuel vapour zone. A fuel vapour zone is defined as an environment in which flammable mixtures can be expected to occur as a result of a fault causing spillage or leakage and where an explosive atmosphere may be present. Examples of regions where this condition may apply could include fuel tanks, wingtips and fuel pipe interfaces. It is, therefore, necessary to ensure that the number and spacing of the cable routing clips provided in particular regions of the airframe are sufficient to meet the safety requirements.